Machine tool
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     This invention relates to a machine tool which has a table for mounting a workpiece. 
     2. BAckground Art 
     Machining operations of a cylindrical workpiece, for example, will be explained hereinafter. In the case of a turning operation of the outer cylindrical surface of a workpiece and a slotting operation of the flat end portion thereof, the workpiece must first be supported between a spindlehead of a lathe and a tailstock of the lathe. After that, the workpiece is removed from the lathe and then mounted on a table of a vertical milling machine. The table is horizontally moved and a slot is produced in the end portion of the workpiece by rotating an endmill. 
     In practice it is troublesome to remove the workpiece from the lathe to the vertical milling machine for performing the machining operations. In addition, since both the lathe and the vertical milling machine are necessary for the machining operations, considerable floor space is required to accommodate both the lathe and the vertical milling machine. 
     SUMMARY OF THE INVENTION 
     In order to solve the aforenoted problems, a main object of this invention is to provide a machine tool which can perform a plurality of operations, such as turning and milling. 
     According to this invention, provision is made for a machine tool which has a table for mounting a workpiece thereon so as to machine the workpiece, characterized in that the table is provided with a rotary table. 
     Accordingly, the machine tool of this invention can perform several operations, such as turning and milling. Thus, it is not necessary to reset or remove the workpiece from a machine tool to another machine tool. Furthermore, it is easy to machine the workpiece. In addition, the machine tool according to this invention reduces the number of machines required and as a result the installation floor space need not be as large as with several machines. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 schematically shows a machine tool according to this invention. 
     FIG. 2 is a front view showing, partly in cross-section, of the machine tool. 
     FIG. 3 is a side elevational view showing, partly in cross-section, of the machine tool. 
     FIG. 4 is a plan view showing the machine tool. 
     FIG. 5 is a perspective view showing a table and a rotary table. 
     FIG. 6 is a side elevational view, with portions broken away, of a spindlehead. 
     FIG. 7 illustrates a condition in which turning operation of a workpiece is performed. 
     FIG. 8 illustrates a condition in which slotting operation of the workpiece is performed. 
     FIG. 9 is a perspective view showing the workpiece having a slot. 
     FIG. 10 illustrates a condition in which a drilling operation of the workpiece is performed. 
     FIG. 11 is a perspective view showing the workpiece having a drilled hole. 
     FIG. 12 is a perspective view showing a workpiece mounted on both the table and the rotary table. 
     FIG. 13 illustrates a condition in which drilling operation of a workpiece is performed in the end face of the workpiece. 
     FIG. 14 and 15 are perspective views showing other embodiments of tables and rotary tables of this invention. 
     FIG. 16 shows a spindlehead equipped with a turret member. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 schematically shows this invention. A body 1 of a machine tool is equipped with a table 2. The table 2 is also equipped with at least a rotary table 3. 
     Referring now to FIG. 2, a base 4 of the body 1 has the table 2, the rotary table 3 and a motor 5. A CNC unit 8 is arranged near the base 4 of the body 1. A pulley 10 is attached to an output shaft 9 of the motor 5 while a pulley 12 is attached to a shaft 11a of a gear box 11. A toothed belt 13 (FIG. 3) is arranged between the pulleys 10 and 12. The shaft 11a can transmit power to a shaft 14 by way of gears (not shown). The rotary table 3 is fixed for rotation on an upper portion of the shaft 14. 
     An automatic tool changer 7, publically known, is provided with a plurality of tools, such as a tap 15, a drill 16 and an endmill 80. 
     A spindlehead 20 is provided with the automatic tool changer 7, a spindle 21, and a turret member 22. An endmill 72 is mounted in the spindle 21. The turret member 22 detachably holds a plurality of tool bits 23 for turning operations. 
     Referring to FIG. 3, a column 6 is fixed on a first sliding member 26. A nut 27 is fixed to an underside of the first sliding member 26. A second sliding member 28 is equipped with a pair of guide rails 29, 29 (FIG. 4). Also, a servomotor 30 is mounted in the second sliding member 28. A feed screw 31 of the servomotor 30 engages the nut 27. The feed screw 31 can be rotated by the servomotor 30. By operating the servomotor 30, the first sliding member 26 can be moved along the guide rails 29, 29 of the second sliding member 28 in the direction of arrow Y 1  or arrow Y 2  (FIG. 3). 
     Guide rails 32, 32 are horizontally arranged on an upper portion of the base 4. The second sliding member 28 can be moved on the guide rails 32, 32. The second sliding member 28 has a nut 33. The nut 33 and a feed screw 34 engage each other. 
     The spindlehead 20 is provided with a nut 43. The nut 43 and a feedscrew 42 engage each other. The feed screw 42 can be rotated by a servomotor 41. Accordingly, the spindlehead 20 can be moved by operating the servomotor 41 along the pair of the guide rails 40, 40 (FIG. 4) in the direction of the arrows Z 1  or Z 2  (FIG. 3). The spindlehead 20 is provided with a motor 44 and an actuator 45. 
     A chuck 46 is detachably mounted on the rotary table 3. The workpiece W is clamped by plurality of jaws 47 of the chuck 46. The chuck 46 is a conventional chuck, such as a hydraulic power chuck. 
     FIG. 4 clearly shows the pair of guide rails 40, 40, the guide rails 29, 29 and a servomotor 50. By operating the servomotor 30, the first sliding member 26 and the column 6 can be moved in the direction of arrows Y 1 , or Y 2  In addition, by operating the servomotor 50, the first sliding member 26, the second sliding member 28 and the column 6 can be moved in the direction of arrows X 1 , or X 2  with respect to the base 4. 
     FIG. 5 shows the table 2 and the rotary table 3. A hole having a circular cross-section 56 is formed in the center portion of the table 2. The rotary table 3 is rotatably arranged within the hole 56. The table 2 is not a rotary table and is fixed on the base 4. T-slots 57 to 59 are machined in the table 2 along the longitudinal direction thereof for this embodiment. Also, T-slots 60 to 62 are machined in the rotary table 3. As the rotary table 3 is in an initial position, shown in FIG. 5, the T-slots 57 to 59 are aligned with the T-slots 60 to 62, respectively. 
     FIG. 6 shows the interior of the spindlehead 20. A gear 64 is attached to an output shaft 63 of the motor 44. A gear 66 attached to a shaft 65 engages the gear 64. A gear 65a attached to the shaft 65 engages a gear 68 of a shaft 67. The shaft 67 connects with the spindle 21. Thus, the spindle 21 can be rotated by operating the motor 44. The spindle 21 is equipped with a collet chuck (not shown). By operating the actuator 45, a holder 74 for the endmill 72 can be held in or removed from the collet chuck. 
     Still referring to FIG. 6, a gear 70 is attached to a servomotor 69. A gear 71 of a cylindrical portion 70a engages the gear 70. The cylindrical portion 70a is constructed in one-piece with the turret member 22. The spindle 21 passes through the cylindrical portion 70a. Thus, by operating the servomotor 69, the turret member 22 can rotate in the clockwise direction or counter-clockwise direction for positioning operations. 
     The above mentioned motors and servomotors are controlled according to the program of the CNC unit 8. 
     OPERATION 
     Referring to FIG. 3, the spindlehead 20 is positioned in an initial position P. The servomotor 41 is operated to thereby move the spindlehead 20 in the direction of arrow Z 1 . 
     Referring to FIG. 7, the endmill 72 has been attached in the spindle 21. After that, the spindlehead 20 is moved in the direction of arrow X 1 , and the rotary table 3 rotates relative to the table 2. Thus, a toolbit 23 starts to machine the outer surface of the workpiece W. As the spindlehead 20 is moved down in the direction of the arrow Z 1 , along a predetermined distance, the turning operation of the outer surface of the workpiece W can be performed. After that, the spindlehead 20 is moved in the direction of arrow Z 2  to remove the toolbit 23 from the workpiece W. 
     Referring to FIGS. 8 and 9, a slot C will be produced in the upper side of the workpiece W. The spindlehead 20 is moved in the direction of the arrow X 1  and moved down in the direction of arrow Z 1 . Thus, the endmill 72 of the spindle 21 is moved toward the upper side F of the workpiece W. After that, the spindlehead 20 is moved down to a predetermined depth of cut in the direction Z 1  and then moved along a predetermined distance in the direction of arrow X 1 . Accordingly, the slot C in FIG. 9 can be produced. After producing the slot C, the spindlehead 20 is moved in the direction of arrow Z 2 , and then moved to the initial position P. After that, the endmill 72 of the spindle 21 is exchanged for a drill 16 of the automatic tool changer 7. The exchanging operation is performed by a conventional exchange arm. 
     Referring to FIGS. 10 and 11, the spindlehead 20 is moved in the directions of arrows X 1 , and Z 1 , to advance the drill 16 toward the upper side F of the workpiece W. After that, the spindlehead 20 is moved in the direction of Z 1 , to produce a hole H having a predetermined depth at its predetermined position of the workpiece W. After that, the spindlehead 20 is moved back to the initial position P. 
     As can be seen from the foregoing, the turning operation of the outer surface of the workpiece W, the production of the slot C and the production of the hole H are performed in the above-mentioned manner. 
     Referring to FIG. 12, a workpiece W1 having a relativity large rectangular shape is mounted on both the table 2 and the rotary table 3. A head 82 of a bolt 81 is fitted into each of the T-slots 57, 59. A male-screw portion 84 of the bolt 81 passes through a hole of a holder 83. A male-screw portion 84 engages a nut 83a. On the other hand, a head of a bolt 81 is fitted into each of the T-slots 60, 62. Each bolt 81 is held by a holder 83. The workpiece W 1  is fixed on the table 2 and the rotary table 3 by means of the four holders 83. The endmill 80 is mounted in the spindle 21 and thus produces a slot C 1 , for example, in the workpiece W 1 . 
     Referring to FIG. 13, a special universal head 100 is mounted in the spindle 21 for this embodiment. An universal head disclosed in Japanese Patent Application No. 60-254886 can be used as the universal head 100. A drill 90 is mounted in the universal head 100. By turning the drill 90, there is produced a hole in a side face of the workpiece W 2 . The workpiece W 2  is fixedly mounted on both the table 2 and the rotary table 3. 
     In the embodiment, it is easy to make arrangements for machining because the table 2 is fixed. If the workpiece W 2  is mounted on the table by a robot, it is easy to position the workpiece on the table 2. 
     FIGS. 14 and 15 show other embodiments of a table and rotary tables. FIG. 14 shows rotary tables 103, 103 which are rotatably arranged at the both sides of the table 102, respectively. 
     In an embodiment of FIG. 15, holes 112a, 112a each having a circular cross-section are machined in a table 112. A rotary table 113 is arranged within the hole 112a. 
     FIG. 16 shows an embodiment in which a turret member 122 is rotatably attached to a side portion of a spindlehead 120. The turret member 122 is equipped with a multitude of toolbits 23. The turret member 122 can be rotated and positioned by a servomotor 169 equipped within the spindlehead 120. 
     This invention is not limited to the above-mentioned embodiments. 
     For example, the table 2 and the rotary table 3 may tilt with respect to the base. The table 2 and rotary table 3 may be electro-magnetic chucks. The table 2 and the rotary table 3 may be moved in the direction of X 1  or X 2 , in the direction of Y 1 , or Y 2 , or in the direction of Z 1  or Z 2  with respect to the base 4. 
     The chuck mounted on the rotary table 3 may be not only a hydraulic power chuck but also any other type chuck such as a scroll chuck. The rotary table 3 may be indexed by an index servomotor. 
     In addition, a tap may be mounted in the spindle to perform the tapping operation of a workpiece. As can be seen from the foregoing, by selecting tools, the machining operations of the workpiece such as turning, drilling, boring, milling and tapping, that is, the combination of operations for the workpiece can be performed.